Magnetic material



Patented Jan. 6, 1931 UNITED STATES PATENT oer-"Ice Jor'm 11. WHITE, or exam-om), AND vrc'ron n" LEGG, or mmwoon, new .1mm, assrenons 'ro BELL'TELEPHONE Lanomroams, INCORPORATED, or NEW YORK,

N. 'Y., A CORPORATION 01 NEW YORK I I MAGNETIC MATERIAL No Drawing.

The present invention relates to the production of magnetic materials and particu-- larly to a" method for producing such mate rials in finely divided form.

' 5 An object of the invention is to facilitate crease the yield of finely divided dust re-' sulting from working the alloys mentioned 0 into finely divided form.

i The invention is of particular advantage in the manufacture of magnetic loading coil cores in which the core is composed of finely divided magnetic material, usually referred to as dust, heldtogether by a? binder.

In the manufacture of such magnetic cores it is customary to subject the materials in solid form to mechanical working such as hot rolling, etc. After such rolling, the materials are converted into a finely ivided or dust form by subjecting them to comminution.

molybdenum is a constituent of the magnetic materials of'the type mentioned, .the hot rolling operation, instead of being conducive to producing a material which will subsequently readily breakup when subjected to tho eiiect of comminuting agents, will on the contrary-toughen it. It has been observed that molybdenum bearing materials such as those mentioned tend to crack deeply during rolling at temperatures of 900 to 1000 0., become oxidized in the cracks, and then break up prematurely into relatively large fragments which willnot give a satisfactory yield of finely divided material when subsequently comminuted.

In accordance with the present invention the premature breaking up during hot rolling "is prevented by adding copper to'the mag-' It has been found that whenever Application and November :0, 1929; Serial Io. 410,861.

netic materials. In a s ecific preferred embodiment of the invention, nickel, iron and copper are melted together in approximately the following proportions: 7 8 nickel, 13 iron and 4% copper. Then about of aluminum is added to the liquid mix 'ture for deoxidizing the bath. After deoxidation about 4% molybdenum is added and the healt teemed and allowed to cool. After solidification the ingot is hot rolled in four I passes at about 1200"C., the total reduction.

being from to diameter. Following this the bar thus obtained is reduced toi dlameter by rolling it at about 1000 C. and is then quenched in water. The bar is then broken up in a rock crusher to pass a 3 mesh screen, after which operation the material is placed in a ball mill and ground for about 20 hours. A yield of 85% in fine dust passing a 120 mesh screen, as against a yield of without the addition of copper, was produced b the methods of this invention.

The met od above described may also be applied when it is desired to reduce to a finely divided state alloys of nickel and iron and alloys of nickel, iron and cobalt which contam chromium or tungsten instead of molybdenum, since it has been found that these two elements are equivalents of mol bdenum as regards their effect upon the fria ility at red heat of the alloys mentioned. 1

Copper added to the magnetic materials as described above apparently has no beneficial electrical or magnetic efiectsthereupon. The permeability, resistivity and other ma netic and electric properties are not improved; the action of the copper is beneficial only from a mechanical viewpoint, that is, the copper acts to im rove the workability of the alloys when red 0t.-

What is claimed is:

1. The method of increasing the yield of fine dust resulting -fron'- reducing magnetic materials includin common elements'of the chromium groupo the periodic table to finely divided form, which method comprises meltingsaid materials with metallic copper, whereby premature breaking up into large fragments during mechanical hot workin is avoided, hot working the materials and subjecting them to a comminuting operation.

2. In the method of preventing cracking in the early passes during hot rolling of. magnetic materials containing molybdenum, the step which includes adding metallic copper to the molten material, hot working it and then comminutin it.

3. A method (ii-producing a high yield of dust when comminuting magnetic materials containing considerable portions of nickel and also of iron and small proportions of common elements of the chromium group of the periodic table, whereby premature breaking up into large fragments during mechanical hot working is avoided, which method comprises incorporating in said material, by melting up to about 4% of copper, hot working the materials and comminuting them after cooling.

In witness whereof, I hereunto subscribe my name this 28th day of October, 1929.

, JOHN H. WHITE. I

In witness whereof, I hereunto subscribe my name this 11 day of November, 1929.

VICTOR E. LEGG.

memos 

